Jean-Claude Juncker is a wily and formidable operator with a strong motive to resent Britain that is rooted in David Cameron’s campaign to stop him taking the European Union’s most powerful job.

As European Commission president he will be prepared to cut a deal with Britain, even to hand powers back from Brussels to Westminster but the abrasive, hard-drinking and heavy-smoking Luxembourger is not inclined to make life easy for the British government.

While Mr Juncker, 59, respects the British as a “common sense and down to earth people”, he is much less tolerant of Britain’s prime minister and Conservatives he sees as being linked to a dirty press campaign against him.

There is history. Ever since the beginning of his political career in the Eighties, Mr Juncker blamed Margaret Thatcher, and successive British governments, for attacking and dismantling the European consensus on “social Europe”, one of his key political beliefs.

While he is relaxed about Britain not joining the euro, he bears a deeper grudge against the United Kingdom for obstructing “closer political union”, particularly for triggering the referendums that destroyed the European constitution a decade ago.

There are other more recent resentments.

Born in 1924 to a working class family, Mr Juncker’s father Joseph, a steel worker and a Christian trade unionist, was forcibly conscripted into the German Wehrmacht army during the War.

In 1942 over 10,000 Luxembourgers were forced to serve in the German army, prompting a nationwide general strike that was brutally crushed by the tiny Grand Duchy’s Nazi occupiers.

The wounds are still raw. In 1997, the Luxembourg leader wept in the margins of an EU summit with Ukraine recalling how his father was wounded fighting in Odessa under duress as a forced conscript in a Nazi army that he loathed.

Over 2,800 of the forced conscripts from Luxembourg died, a history that reinforces Mr Juncker’s mission to keep a reunified Germany bound to France within European structures, such as the euro.

Last month, his father, aged 90, who is frail and living in nursing home, wept when a radio station reported on The Sun newspaper’s allegation that he was the Juncker family’s “Nazi link”, an episode that has hardened his son’s hostility to British opposition to his appointment.

“He was stunned,” said a source close to Mr Juncker. “He despairs that the disgusting part of the British press has such a large influence.”

Mr Cameron’s staunch opposition to him being appointed Commission president, including Downing Street briefings on his heavy drinking, have confirmed Mr Juncker’s opinion that he must work to bypass Britain in order to stop it obstructing deeper European integration.

“We don't include the UK in our plans anymore. We assume you're leaving the EU so don’t assume we even bother thinking about British objections,” said Mr Juncker’s closest aide recently.

Famous for his sarcasm, heavy drinking and chain smoking, Mr Juncker is not known to have other interests outside politics. He is married, but has no children. According to friends he has a collection of newspaper cuttings and can pinpoint a quote or moment in his political career by pulling out a file.

“He never forgets,” said the friend.

A modest and secretive man, Mr Juncker, whose country combines both Germanic and French influences, has been relied on by three successive generations of German chancellors and presidents of France as their preferred fixer, a key link in the euro structures that bind Paris and Berlin.

While he dismisses claims that he believes in a “United States of Europe”, he does have a vision of a federal EU where nations continue but have the constitutional status of regions in the German constitution bound by higher authorities, such as the European Commission or Central Bank.

He is both pragmatic and ruthless because he sincerely believes that the EU and euro is all that stands between Europe and war.

Europe’s “demons haven't been banished; they are merely sleeping” he warned last year amid eurozone tensions.

So strong is his commitment to the EU that Mr Juncker is prepared to deliberately mislead the public, to ignore referendum votes and, in a bitter twist, to impose savage austerity in the eurozone, sweeping aside social Europe, to defend the euro.

Mr Juncker has never hidden his view that the compromises and deals being worked out in EU meetings or leaders or ministers need be protected from public scrutiny, by lies if necessary.

His methods, combined with Luxembourg's sometimes sinister political culture, have rung alarm bells.

Until last year, Mr Juncker dominated politics in Luxembourg for a generation, serving as prime minister for 19 years and running the Grand Duchy as a fiefdom. His regime, mirroring his own tendency to be secretive, had a dark side in the form of the Luxembourg’s sinister security services, the SREL, which holds a file on almost every resident.

He resigned last year after a bizarre scandal involving telephone tapping by Luxembourg’s intelligence service, including a conversation between him and his spy chief that was taped on a recorder disguised as a wristwatch.

There have been other revelations. Roger Mandé served as Mr Juncker’s personal chauffeur for over a decade but wanted a more glamorous career than the humdrum life of a professional driver. In 2006, Mr Mandé became a spy, joining the secret service after a personal intervention from Mr Juncker.

Many in Brussels are concerned that Mr Juncker will bring Luxembourg’s political culture with him when he comes to the commission. This is a concern because in March 1999 under the leadership of Jacques Santer, its last Luxembourger president, the commission collapsed in ignominy amid scandals over endemic corruption and nepotism.